This project is designed to determine the response to varying degrees of GnRH receptor blockade in normal men and women, postmenopausal women and patients with reproductive endocine disorders. This has been an extremely active protocol and a significant number of publications have resulted from these studies. In the past year, the investigators have completed their studies in GnRH deficient men, a model in which it is possible to quantitate the relationship between GnRH and GnRH receptor blockade. In addition, in this past year the investigators have published their studies in patients with polycystic ovarian syndrome (PCOS) in which they showed that the LH response to incomplete receptor blockade was not different than in women in the follicular phase. These data suggest that the increased frequency of pulsatile GnRH secretion, which they had previously found in PCOS, is not associated with an overall increase in the amount of GnRH secreted. Complete GnRH receptor blockade was used to examine the effect of LH on androgen secretion in acute and short-term studies. Results provided further evidence for dependence of androgen secretion on LH, but also indicated that testosterone levels decreased by only 40%, even with 7 days of LH inhibition. The investigators have also used complete GnRH receptor blockade to examine the changes in plasma disappearance of LH in postmenopausal vs normal cycling women and determined that the disappearance rate is approximately doubled after menopause in studies that are in press. The lack of an effect on FAS suggested that these changes following menopause were due to changes in the isoforms of LH. Collaborative studies have not shown that the isoforms of LH in these postmenopausal women are more acidic than reproductive aged women and that mobility of LH on isoelectric focusing is correlated with the calculated disappearance.